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Rear Tire Rapid Pressure Loss - Rear Brake or Not?

A friend of mine had a rapid pressure loss in the rear tire of his Yamaha touring bike yesterday. The result turned into a fishtail from 65 mph down to around 30 where he and his girlfriend finally left the bike. They received some nasty road rash, but thankfully did not hit anything. I quizzed him on how he reacted to the event, and he said he never hit the rear brake. He only used the front to try to scrub off speed, but the fishtail continued to worsen to the point of get-off.

My question for the MSF professors and others with experience out there is will judicious rear brake use possibly pull a bike back from a nasty fishtail in an event like this?

The MSF curriculum recommends that you use the brake on the "good" wheel, as your friend did. I can't see anything good coming from trying to brake on a flat tire. If the bead breaks free you have no braking force anyway, and if the tire dismounts completely, it is almost always a very bad thing.

Rear flat and fishtail

Depending on how heavy the bike was and how the weight was distributed, all sorts of crazy things can happen to cause fishtail. On top of that, a passenger will tend to stiffen up or move contrary to what's required to remain stable, which exacerbates the problem.

Sure glad to hear your friends will be okay.

Whatever the reason for the deflation, it's another reminder to inspect tires closely and regularly, watch out for road hazards, and replace tires before they're thin.

If anything good can come from a crash (strange thought), the good thing is he found a pristine 2003 K1200LT as a replacement bike after the insurance totaled his Yamaha cruiser/tourer. And as of yesterday, he is a MOA member. David said he likes the idea of BMW riders actually riding a bike after he met up a couple of times with our local club, Lone Star BMW Riders.

Good question. I've had only one flat tire (crossed fingers) and it was the rear on my K1200RS - with linked brakes (front & rear off the front). So to use the front brake I couldn't not use the back. I was running about 75 making a big sweeping corner when the bike felt funny. A quick flick of the bars confirmed a problem so I slowed and pulled over. The last of the air was came out of the rear tire as I got stopped. No drama - this time. You only have seconds to take action when a tire is going flat.

Slow down with as little input to the rear as possible. Pull in the clutch and let that wheel coast. Of course with the linked brake gadget you are screwed as the machine won't let the rider decide how or what brakes to apply in any given situation.

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The problem your friend had ,was that he had only one flat tire! Had both tires deflated at the same time, he would have found that the bike won't roll very far with no air in the tires. No brakes needed at all!

The problem your friend had ,was that he had only one flat tire! Had both tires deflated at the same time, he would have found that the bike won't roll very far with no air in the tires. No brakes needed at all!

The wheels of my R1150RS in the pictures.

I would be curious to know WHAT THE HECK you ran over or into to cause that kind of trauma to your wheels??!!

Just glad you're around to tell us about it.

As for the information that began this thread, unfortunately there are scenarios that will have no happy endings, and this may be one of them.

Rapid air loss in a tubed tire is rare unless the damage is catastrophic, as in a large slash or severe damage to the rim / bead.